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      03-28-2017, 07:42 AM   #1
pfitz911
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increasing tyre sidewall 17s

Hi guys
I have a 330i with 17 225 45 tyres. I drive long distances so I want as much comfort as possible. I have read about not going much more in tyre size due to transmission and speedo concerns, but Im kinda keen to get a bit more tyre on my rim. The profile looks too low for 17s, would love to go 225 50 17 but Im thinking it might be too much?
Why would this tax my tranny when f30s run 50 series?
Second, whats a good quiet well priced tyre you guys could recommend?
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Dan
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      03-28-2017, 08:20 AM   #2
Ken Oath
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Original tyre 225/45 R17
New tyre 225/50 R17

Diameter change would be 3.6% or 23mm.

In SA the tyre and wheel diameter combination cannot be more or less than 15mm from the manufacturers specification.
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      03-28-2017, 08:27 AM   #3
pfitz911
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So what would you suggest? what about 215 50 17?
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      03-28-2017, 08:53 AM   #4
Ken Oath
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Quote:
Originally Posted by Wolf 335 View Post
101.25mm sidewall - current setup

112.5mm sidewall - desired setup

overall increase in overall diameter including 17" rim and desired tire sidewall =
17"(431.8mm) + 112.5mm = 544.3mm (21.43 inch)
Canuck math?

431.8 + 112.5 + 112.5 = 656.8mm

A tyre has two sidewalls.
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      03-28-2017, 09:34 AM   #5
Wolf 335
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Quote:
Originally Posted by pfitz911 View Post
So what would you suggest? what about 215 50 17?
Sorry didn't get a chance to finish that earlier post. I edited my previous post.

with a 50 sidewall you will not have any negative effects.

If you go to 215/50/17, you will actually be reducing the side wall height than if you go with a 225/50/17.

Keep in mind the second number in tire sizing is a % of the tire width (first number).

Last edited by Wolf 335; 03-28-2017 at 09:44 AM.
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      03-28-2017, 10:11 AM   #6
Ken Oath
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Quote:
Originally Posted by Wolf 335 View Post
101.25mm sidewall - current setup
17"(431.8mm) + 101.25mm = 533.05mm (21 inches)


112.5mm sidewall - desired setup
17"(431.8mm) + 112.5mm = 544.3mm (21.43 inches)

**Overall increase in overall diameter including 17" rim and desired tire sidewall is 21.43" - 21" = .43" (10.92mm)

This increase is not significant enough to cause any negative effects on the vehicle.

225/45 R17

D1 = 634mm
where Rim D = 432mm
Sidewall H = 101mm

101 + 101 + 432 = 634mm


225/50 R17

D2 = 657mm
where Rim D = 432mm
Sidewall H = 113mm

113 + 113 + 432 = 657mm

Therefore:
D2 - D1 = 23mm Overall increase in D. No joke.


http://www.inawise.com/tyre-calculat...alculator.html
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      03-28-2017, 11:16 AM   #7
Wolf 335
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Quote:
Originally Posted by Ken Oath View Post
225/45 R17

D1 = 634mm
where Rim D = 432mm
Sidewall H = 101mm

101 + 101 + 432 = 634mm


225/50 R17

D2 = 657mm
where Rim D = 432mm
Sidewall H = 113mm

113 + 113 + 432 = 657mm

Therefore:
D2 - D1 = 23mm Overall increase in D. No joke.


http://www.inawise.com/tyre-calculat...alculator.html
Why are 2 sidewalls being added to calculate the diameter. I don't understand. If that's the case then you would be adding 2 wheel diameters as well.
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      03-28-2017, 11:31 AM   #8
Ken Oath
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The calculation is determining the overall D (or height if you prefer) of the tyre and the rim.

See the attached image. You have only accounted for one section height.
There is two sidewalls as previously described. The OP question was answered in my first post and remains.

If you visit any web tyre calculator the answer I provided will still remain.
No joke.
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      03-28-2017, 11:59 AM   #9
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Quote:
Originally Posted by Ken Oath View Post
The calculation is determining the overall D (or height if you prefer) of the tyre and the rim.

See the attached image. You have only accounted for one section height.
There is two sidewalls as previously described. The OP question was answered in my first post and remains.

If you visit any web tyre calculator the answer I provided will still remain.
No joke.
Oh wow, complete brain fart on my end.

My apology. You are correct sir. No joke haha!

I have deleted my previous posts with missing calculation.
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      03-28-2017, 07:10 PM   #10
pfitz911
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So...your saying 225 50 is illegal, but 215 50 will actually decrease diameter??
Do I just stay with 225 45??
Cheers guys
dan
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      03-28-2017, 07:12 PM   #11
pfitz911
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sorry...looking to buy some tyres online. what brand is good to avoid tramlining/quiet/well priced. is there a rating I should hve
thanks again
Dan
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      03-28-2017, 07:33 PM   #12
bradsm87
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If you want comfort, get normal non-runflat tyres in the factory size and get a space saver spare to keep in the boot. 225/45 is plenty of sidewall and provides lots of comfort in a normal non-runflat tyre.
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      03-28-2017, 10:46 PM   #13
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225/50 R17
Is a 23mm increase in overall D and not acceptable in SA.

215/50 R17
Is a 12.5mm increase in overall D so that is acceptable.

I previously had 225/45 R17 Goodyear Eagle F1 and they are notorious for tramlining. Swapping to Conti Sport Contact 5 improved everything dramatically and was getting good wear until I sold the vehicle.

As already mentioned avoid RFT.

http://www.tirestest.com
https://www.tirerack.com/tires/revie...surveyComments
http://www.e90post.com/forums/showthread.php?t=720790
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      03-30-2017, 06:51 AM   #14
pfitz911
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Thanks guys
I reckon Im gonna give 215 50s a go...
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      04-02-2017, 09:33 AM   #15
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Instead of going for a narrower tyre. Why not go for 235/45-R17.
Its a 10mm wider tyre and also larger diameter by about 10mm.

Other benefits:
* Its a popular size for non-RFT, so costs less.
* Also provide larger contact area, so you can drop the air pressure by 1 PSI.
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      04-20-2017, 09:45 PM   #16
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Quote:
Originally Posted by John_01
Instead of going for a narrower tyre. Why not go for 235/45-R17.
Its a 10mm wider tyre and also larger diameter by about 10mm.

Other benefits:
* Its a popular size for non-RFT, so costs less.
* Also provide larger contact area, so you can drop the air pressure by 1 PSI.
Not sure about the pressure drop, as with a larger surface area of rubber you'll need more pressure to keep everything stable.
Bridgestone told me in my 275s to go up a couple pound just for the support.
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      04-21-2017, 10:14 PM   #17
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Putting a 235/45 tyre on a 8" wide rim is very normal and actually recommended. The steering response may change if you are sensitive to such things.
If you want good cornering stability and steering response, you should choose a sporty tire design with firm sidewall stiffness.
Tire choice depends on your priorities though.
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      04-22-2017, 08:59 AM   #18
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As others have suggested, going to a quality non-RFT is the best option for you. A 45 profile tyre is already a big marshmallow. Michelin Pilot Sport 3 is quiet and decent.

Adjust pressures to suit your comfort and tyre wear desires
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